A. Technical Field
The present invention relates to a catalyst for production of acrylic acid and a process for production of acrylic acid using this catalyst.
B. Background Art
As to catalysts for efficient production of acrylic acid by catalytic gas phase oxidation of acrolein (catalysts for production of acrylic acid), there is widely used a catalyst comprising molybdenum and vanadium as essential catalytic components, and various proposals have been made about its production processes.
Examples of these production processes include: (a) a process in which a mixed liquid of starting materials is subjected to evaporation to dryness, and then, to the resultant dried material, there are added polyvinyl alcohol, a water-absorbent resin, and water, and then they are kneaded together and then extrusion-molded (e.g. refer to patent document 1 below); (b) a process in which a mixed liquid of starting materials is spray-dried and then calcined at 400° C., and then the resultant calcined material is supported onto a support with water as a binder by use of such as a rotary drum type supporting device (e.g. refer to patent document 2 below); (c) a process in which a mixed liquid of starting materials is dried by any method of evaporation to dryness, spray drying, drum drying, and gas flow drying, and then, to the resultant dried material, there are added propyl alcohol and water to mix them together, and then the resultant mixture is extrusion-molded (e.g. refer to patent document 3 below); (d) a process in which a mixed liquid of starting materials is spray-dried and then calcined at 400° C., and then the resultant calcined material is supported onto a support with a liquid binder comprising water and an organic compound of higher than 100° C. in boiling point or sublimation temperature under normal pressure (e.g. refer to patent document 4 below); and (e) a process in which a mixed liquid of starting materials is dried and then calcined at 250-500° C., and then the resultant calcined material is supported onto a support with such as aqueous glycerol solution as a binder by use of a tumbling granulator (e.g. refer to patent documents 5 and 6 below).                [Patent Document 1] JP-A-096183/1993 (Kokai)        [Patent Document 2] JP-A-279030/1994 (Kokai)        [Patent Document 3] JP-A-010621/1996 (Kokai)        [Patent Document 4] JP-A-252464/1996 (Kokai)        [Patent Document 5] JP-A-299797/1996 (Kokai)        [Patent Document 6] JP-A-079408/2001 (Kokai)        
However, still none of the catalysts for production of acrylic acid which catalysts are obtained by the above prior production processes is sufficient for the aim of the selectivity of acrylic acid which is the objective product. Furthermore, still none of these catalysts can be said to be sufficient for the aims that chemical and physical properties (e.g. properties such as specific surface area, pore volume, pore distribution, acidity/basicity, acid strength/basic strength) of the catalysts are stable for a long time and further that the catalysts enable the efficient production of acrylic acid. Therefore, there has been much room for improvement.